Re: FAQ and string functions

[bam@snoopy.apana.org.au (Brian May)]

> Strings in Ada are particularly tricky for newcommers. One trap is
> underuse of perfectly sized string constants. Most strings get their
> value once and never need it changed. If that is the case, its fairly
> easy to declare the string at the point its value is known, with the
> perfect bounds, by using a string constant (possibly inside a
> "declare" block). If you do that, it becomes very easy to deal with.

I have two questions concerning strings that I can't find answers for
in the RM:

1. How do I split a string up into tokens and iterate through the list
of tokens (compare with C's strtok function)?

2. Can this ugly looking code be simplified?

      declare
         I    : Iterator;
      begin
         I := Element_Iterator(Class_Element,"parent");
         while More(I) loop
            declare
               My_Node : Node renames Value(I);
               Class_Ref : DOM_String renames
Get_Attribute(My_Node,"ref");
            begin
               Put_Line(Class_Name(Package_Id,Class_Ref)&"($1,$2,$3)");
            end;
            Next(I);
         end loop;
         Free(I);
      end;

where Element_Iterator, More, Value, Next, and Free are my own
functions to iterate over elements in a DOM tree in xmlada (without
these the code was a real mess). DOM_String is similiar to a string
(in fact, I think internally it is defined as a string, but don't
quote me on that).

Ideally I don't want to have the nested declare block for the sole
purpose of
saving the result from Get_Attribute, but I am not sure this is
possible?

eg. I would like to be able to say

      declare
         I    : Iterator;
         Class_Ref : DOM_String;
      begin
         I := Element_Iterator(Class_Element,"parent");
         while More(I) loop
            Class_Ref := Get_Attribute(Value(I),"ref");
            Put_Line(Class_Name(Package_Id,Class_Ref)&"($1,$2,$3)");
            Next(I);
         end loop;
         Free(I);
      end;

but do it in a legal way. I think this would make the code more
readable.

Any comments?